redrafted the design

README.md

@@ -1,30 +1,20 @@
-# hl
+# libhl 
-General purpose highlighter.
 
-	// it would be lovely to have a different name the "library" part and the cli
+## API
+	int hl_init(void);
+	int hl_deinit(void);
+These functions are responsible for the library's "life time".
+`hl_init()` must be called before any other library function.
+`hl_deinit()` will ensure all occupied memory is freed.
 
-# Usage
-hl will read from stdin and write to stdout.
-	hl < source/main.c
-
-### Cli Options
-	-h          : display help message
-	-F <dir>    : syntax file look up directory
-	-s <syntax> : specify syntax to load
-
-### Environment variables
-	HL_HOME	: default directory to load syntax files from
-
-# API
 	void render_string(const char * const string, const char * const mode);
-This function matches _string_ against all known highlighting rules and dispatches the appropriate callback defending on mode.
+This function matches _string_ against all known highlighting rules and dispatches the appropriate callback depending on _mode_.
 
 	typedef void (*attribute_callback_t)(const char * const string, const int length, void * const attributes);
 The type used for defining appropriate callbacks for render_string().
-	string     - string to be outputed
++ string     - string to be outputed
-	length     - number of characters that matched a highlighting rule;
++ length     - number of characters that matched a highlighting rule
-	              0 if rule passed, in such a case the user is expected still want 1 character outputed
++ attributes - arbitrary data associated with the matched rule; intended to hold color/font information for example
-	attributes - arbitrary data associated with the matched rule; intended to hold color/font information for example
 
 	typedef struct {
 		char * key;
@@ -43,30 +33,49 @@ This is how you append a display mode that render_string() will search based on
 	} token_type_t;
 These are the valid type of distinct token types.
 
-	KEYSYMBOL - a string which is contextless, the surounding text is ignored
++ KEYSYMBOL - a string which is contextless, the surounding text is ignored
               "mysymbol" will match inside all of these:
                  "something mysymbol something"
                  "somethingmysymbolsomething"
-	            it is intended to match such thing as programming language operators,
+              it is intended to match such thing as programming language operators
-	             so both "var a = 'a'" and "var a='a'" are recognized
++ KEYWORD   - a string which is recognized when surounded by word bundaries such as ' ' or '\t'
-	KEYWORD   - a string which is recognized when surounded by word bundaries such as ' ' or '\t'
++ MATCH     - a regular expression to be recognized
-	MATCH     - a Vim style regular expression to be recognized
++ REGION    - a regular expression where the starting and ending patters are to be distinguished from the contents
-	REGION    - a Vim style regular expression where the starting and ending patters are to be distinguished from the contents
 
 The universal way to add a new pattern to be recognized is with:
 
 	token * new_token(const char * const syntax, const token_type_t t, const hl_group_t * const g);
 
-This wraps one of the following:
-
-	// ?!
-
 There are also convinience functions:
 
 	// NOTE: the return value is the number tokens successfully inserted
-	int new_keyword_tokens(const char * const * words, hl_group_t * const g);
+	int new_keyword_tokens(const char * const * words, hl_group_t * const g);	// _words_ must be NULL terminated
 	int new_syntax_character_tokens(const char * const chars, hl_group_t * const g);
 
+The regex engine used for MATCHes is Jeger by default, emulating Vim regex.
+However the regex engine can be overridden:
+
+	// ?!
+
+---
+
+#hl 
+General purpose highlighter (and demo program for libhl).
+
+## Usage
+hl will read from stdin and write to stdout.
+	hl < source/main.c
+
+### Cli Options
+	-h          : display help message
+	-F <dir>    : syntax file look up directory
+	-s <syntax> : specify syntax to load
+
+### Environment variables
+	HL_HOME	: default directory to load syntax files from
+
+---
+
 # Scripting
 hl can parse a small subset of VimScript: the few instructions related to highlighing, and it ignores everything else.
 All Vim highlighing scripts should be valid hl scripts.